Hello all,

The Dimage scan dual IV has, besides 8 and 16 bit scan modus, also a
16 bit linear modus. The manual is not very clear about its
usefulness, but I have the feelling that it must be good for
something.
Who can enlighten me on the subject, or direct me to an enlightening
link?

Thanks in advance for the response.

--
Greetings,
A.

<Alex> wrote in message news:(E-Mail Removed)...
> Hello all,
>
> The Dimage scan dual IV has, besides 8 and 16 bit scan modus, also a
> 16 bit linear modus. The manual is not very clear about its
> usefulness, but I have the feelling that it must be good for
> something.
> Who can enlighten me on the subject, or direct me to an enlightening
> link?

16-bit/channel linear scan data is the best basis for further
postprocessing. The most significant step, either by the scanner software or
by a photoeditor application, is gamma adjustment to offset the
display/monitor gamma. It is better to apply as many corrections as needed
in a single step rather than in subsequent steps, because each individual
calculation step introduces rounding errors. These errors can cumulate into
visible artifacts.

There will be little visible deterioration from gamma correction by the scan
software, followed by a small number of separate postprocessing steps, but
with each step the data quality will be reduced, so keeping the number of
steps limited to a few is best.

Bart

"Bart van der Wolf" <(E-Mail Removed)> wrote:
>
><Alex> wrote in message news:(E-Mail Removed)...
>> Hello all,
>>
>> The Dimage scan dual IV has, besides 8 and 16 bit scan modus, also
>>a
>> 16 bit linear modus. The manual is not very clear about its
>> usefulness, but I have the feelling that it must be good for
>> something.
>> Who can enlighten me on the subject, or direct me to an
>>enlightening
>> link?
>
>16-bit/channel linear scan data is the best basis for further
>postprocessing. The most significant step, either by the scanner
>software or
>by a photoeditor application, is gamma adjustment to offset the
>display/monitor gamma. It is better to apply as many corrections as
>needed
>in a single step rather than in subsequent steps, because each
>individual
>calculation step introduces rounding errors. These errors can
>cumulate into
>visible artifacts.
>
>There will be little visible deterioration from gamma correction by
>the scan
>software, followed by a small number of separate postprocessing
>steps, but
>with each step the data quality will be reduced, so keeping the
>number of
>steps limited to a few is best.
>
>Bart

Thank you for the explanation. There is still the matter of "16 bit"
versus "16 bit linear" : has one or the other been changed from the
original data as they have been acquired? A gamma correction perhaps?

--
Greetings,
A.

<Alex> wrote in message news:9eOdnaWyKf4-(E-Mail Removed)...
SNIP
> Thank you for the explanation. There is still the matter of "16 bit"
> versus "16 bit linear" : has one or the other been changed from the
> original data as they have been acquired? A gamma correction perhaps?

Yes, gamma correction (making it non-linear) and some basic color balancing.

Bart

"Bart van der Wolf" <(E-Mail Removed)> wrote in message news:<4097a5b2$0$64453$(E-Mail Removed)>...
> <Alex> wrote in message news:(E-Mail Removed)...
> > Hello all,
> >
> > The Dimage scan dual IV has, besides 8 and 16 bit scan modus, also a
> > 16 bit linear modus. The manual is not very clear about its
> > usefulness, but I have the feelling that it must be good for
> > something.
> > Who can enlighten me on the subject, or direct me to an enlightening
> > link?
>
> 16-bit/channel linear scan data is the best basis for further
> postprocessing. The most significant step, either by the scanner software or
> by a photoeditor application, is gamma adjustment to offset the
> display/monitor gamma. It is better to apply as many corrections as needed
> in a single step rather than in subsequent steps, because each individual
> calculation step introduces rounding errors. These errors can cumulate into
> visible artifacts.
>
> There will be little visible deterioration from gamma correction by the scan
> software, followed by a small number of separate postprocessing steps, but
> with each step the data quality will be reduced, so keeping the number of
> steps limited to a few is best.
>
> Bart

I think it interchangable with a Vuescan "raw file", for
scan-from-disk workflow, within that program. Though, I would prefer
to create such "raw file" from within Vuescan. Minolta explained
nothing regarding this format in my Scan Dual II manual.

"Bart van der Wolf" <(E-Mail Removed)> wrote:
>
><Alex> wrote in message news:9eOdnaWyKf4-(E-Mail Removed)...
>SNIP
>> Thank you for the explanation. There is still the matter of "16
>>bit"
>> versus "16 bit linear" : has one or the other been changed from the
>> original data as they have been acquired? A gamma correction
>>perhaps?
>
>Yes, gamma correction (making it non-linear) and some basic color
>balancing.
>
>Bart
>

Hello Bart,
Thank you for the explanation.

--
Greetings,
A.

In article <4097a5b2$0$64453$(E-Mail Removed)>, Bart van der
Wolf <(E-Mail Removed)> wrote:

> <Alex> wrote in message news:(E-Mail Removed)...
> > Hello all,
> >
> > The Dimage scan dual IV has, besides 8 and 16 bit scan modus, also a
> > 16 bit linear modus. The manual is not very clear about its
> > usefulness, but I have the feelling that it must be good for
> > something.
> > Who can enlighten me on the subject, or direct me to an enlightening
> > link?
>
> 16-bit/channel linear scan data is the best basis for further
> postprocessing. The most significant step, either by the scanner software or
> by a photoeditor application, is gamma adjustment to offset the
> display/monitor gamma.

No.

Gamma encoding of the image has nothing to do with the display transfer
function.

Gamma encoding of the image is done to maximize the usage of the bits
for human vision and give the image a nearly perceptual encoding (which
are different ways of saying the same thing).

Chris

"Chris Cox" <(E-Mail Removed)> wrote in message
news:040520042342314690%(E-Mail Removed)...
> In article <4097a5b2$0$64453$(E-Mail Removed)>, Bart van der
> Wolf <(E-Mail Removed)> wrote:
SNIP
> > 16-bit/channel linear scan data is the best basis for further
> > postprocessing. The most significant step, either by the scanner
software or
> > by a photoeditor application, is gamma adjustment to offset the
> > display/monitor gamma.
>
> No.
>
> Gamma encoding of the image has nothing to do with the display transfer
> function.

Nothing, seems a bit too strong. Besides, why is there a different gamma
needed for Mac display versus Windows? The LUTs for video display have a
different gamma encoding that needs to be compensated for.

> Gamma encoding of the image is done to maximize the usage of the bits
> for human vision and give the image a nearly perceptual encoding (which
> are different ways of saying the same thing).

The question is; is the more efficient usage of bits the result, or the goal
of the exercise?
The reciprocal gamma adjustment applied to the scan data, is reversed by the
native gamma of the display. Where has the perceptual encoding gone? It only
adds some accuracy, but has no effect on human perception (which also looks
at a linear gamma real world photon flux). Based on that photon flux, the
human visual system does respond to luminance differences in a somewhat
logarithmic sense.

What's more, also Photoshop does some of its (blending) processing in linear
gamma space, requiring to temporarily reverse the gamma encoding (=loss of
accuracy) of the file.
Major rendering packages often use linear gamma, because it is a benefit for
calculating, but the storage can be done in a number of different encodings
(=coding efficiency/accuracy).

Finally, after all those calculations, the data must be displayed/printed on
a device that has a native gamma, and a compensating correction is needed.

Bart

On Tue, 04 May 2004 04:10:34 -0500, Alex <> wrote:

>Hello all,
>
>The Dimage scan dual IV has, besides 8 and 16 bit scan modus, also a
>16 bit linear modus. The manual is not very clear about its
>usefulness, but I have the feelling that it must be good for
>something.
>Who can enlighten me on the subject, or direct me to an enlightening
>link?
>
>Thanks in advance for the response.
>
>--
>Greetings,
>A.

I have tried using the 16 Bit Linear output on B&W negative scans on
my Dimage dual IV, but the image is clipped in the lowest density
areas of the negative. The main exposure adjustment on the exposure
tab has some effect on the linear image, but it does not eliminate the
extensive clipping. Because of this result specifically with the
Dimage dual IV I would not suggest using it the same way as a Vuescan
raw file unless you check it carefully for full dyanmic range.

The Vuescan raw output with the Diamge dual IV is not clipped like the
Konica Minolta software linear output, so it can produce a usable
image.

"Al" <(E-Mail Removed)> wrote in message news:(E-Mail Removed)...
> On Tue, 04 May 2004 04:10:34 -0500, Alex <> wrote:
SNIP
> I have tried using the 16 Bit Linear output on B&W negative scans on
> my Dimage dual IV, but the image is clipped in the lowest density
> areas of the negative.

Have you tried scanning it as a positive, then invert and gamma adjust in
the photoeditor? It may sound odd, but that should work better than scanning
it as a negative. The Minolta software has a problem scanning negatives
without clipping.

Bart